Päiväkirja-arkisto kohteelle lokakuu 2021

14. lokakuuta 2021

Esterification - Formation of aroma/ester

Esterification - Formation of aroma/ester

An ester is a chemical compound derived from an acid (organic or inorganic) in which at least one –OH hydroxyl group is replaced by an –O– alkyl (alkoxy) group, as in the substitution reaction of a carboxylic acid and an alcohol.

RCO2H + R′OH ⇌ RCO2R′ + H2O

Types of esters

There are two groups of esters, aliphatic and phenolic. Aliphatic esters are those formed with straight chain/non-cyclic molecules (such as alcohols and fatty acids). Phenolic esters are formed from phenolic compounds, which are cyclic in nature.

Example:
Ethanoic acid (Common Name: Acetic acid) CH3COOH
Ethanol C2 H5OH

CH3COOH + C2 H5OH ⇌ CH3COOC2 H5 + H2O

In the presence of a dehydrating agent, e.g. H2SO4, the reaction goes to the right-hand side of the equation:

CH3COOH + C2 H5OH ---> CH3COOC2 H5 + H2O

It is said that aliphatic monocarboxylic esters are the most significant esters for white wines. The second group are those formed from acetic acid and higher alcohols.

Example: Grape phenolic compounds

Lähetetty 14. lokakuuta 2021 07:12 käyttäjältä lunababy22 lunababy22 | 0 kommenttia | Jätä kommentti

1. lokakuuta 2021

More about Photosynthesis: Difference Between Chlorophyll A and B


Category: Cell Biology
From: https://pediaa.com/difference-between-chlorophyll-a-and-b/#ab

Author: Lakna - a graduate in Molecular Biology & Biochemistry, is a Molecular Biologist and has a broad and keen interest in the discovery of nature related things.











































Chlorophyll A (Chemical formula: C55H72MgN4O5) Chlorophyll B (Chemical formula: C55H70MgN4 O6)
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Chlorophyll A is the principal pigment involved in the photosynthesis. Chlorophyll B is the accessory pigment, collecting the energy in order to pass into chlorophyll A
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Three-fourths (¾) of total chlorophyll in plants are Chlorophyll A. One-fourth (¼) of total chlorophyll in plants are Chlorophyll B.
Chlorophyll A absorbs the light in the range of 430 nm to 660 nm (violet-blue and orange-red light from the spectrum). The wavelengths which are effectively absorbed by chlorophyll A are 430 nm and 662 nm. Chlorophyll A reflects blue-green in color. Chlorophyll B absorbs the light in the range of 450 nm to 650 nm (orange-red light from the spectrum). The wavelength which is effectively absorbed by chlorophyll B is 470 nm. Chlorophyll B reflects yellow-green in color.
------------------------------------ ------------------------------------
The solubility of chlorophyll A is low in polar solvents. Chlorophyll A is soluble in petroleum ether. The solubility of chlorophyll B is high in polar solvents like ethanol and methanol compared to chlorophyll A.
------------------------------------ ------------------------------------
Chlorophyll A is present in all the photosynthetic organisms on earth, giving a bluish green color to those organisms. Chlorophyll B gives a yellowish green color to organisms.


Supplementary information:
Visible Color Spectrum Wheel (https://sciencestruck.com/visible-color-spectrum-wheel)

The visible color spectrum wheel is an arrangement of colors in a wheel or circle to show how one color relates to the other.
...... (omitted)

Here is a color wheel from Wikimedia Commons:
Color wheel wavelengths

UV 270nm to 280nm
Violet 400nm
Blue 475nm
Green 510nm
Yellow 570nm
Orange 590nm
Red 650nm

Arrangement of Colors
The wavelength of visible light is between 390 to 750 nm, which is visible to the naked eye in the form of light. In a standard color wheel, all the visible colors are painted on a circle. The three primaries (red, yellow, and blue) are placed around the three points of an equilateral triangle; they are also known as pure colors, as they cannot be made by mixing any other colors.

The secondaries (green, orange, and violet) are then placed in between the primaries at equal distances. They are made by mixing two primary colors in equal proportions. Orange is made by mixing red with yellow; violet is made by mixing red with blue; and green is made by mixing blue with yellow. The six tertiary colors, which are red-orange, red-violet, yellow-green, yellow-orange, blue-green, and blue-violet, are made by mixing each primary color with the adjacent secondary one.

For example, red-orange is made by mixing red (primary) with orange (secondary). Red orange is then placed in between red and orange in the wheel. All the other five tertiary types are placed in it in the same way, i.e., in between the primaries and the secondaries from which they are made.

These 12 colors form the basis of this wheel. However, in reality, there are many more varieties, shades, and hues. Many such wheels show more gradation of colors and have 24 colors on them. In theory, all of them can be made by mixing the primary, with the secondary and tertiary ones; and the total number will be infinite. But in reality, it is very difficult for paint companies to come up with so many variations.

One of the most interesting facts about this wheel is that if it is spinning rapidly, our eyes can see the color white, which is not even there in it. When it spins rapidly, the colors merge into each other very fast, and our mind is not able to distinguish between them. So, their reflection is blended, and we see white light. When all the light of the visible spectrum is absorbed, we see the color black. The color wheel is thus, invaluable for artists as well as physicists, who study the interaction of colors.

Lähetetty 1. lokakuuta 2021 12:13 käyttäjältä lunababy22 lunababy22 | 0 kommenttia | Jätä kommentti

10. lokakuuta 2021

Observations/Identifications of Chamomiles

1. German chamomile or Matricaria chamomilla
Matricaria recutita
> [Matricariinae > Matricaria] > [Matricaria chamomilla]

https://www.inaturalist.org/observations/49426380
June 13, 2020 in Netherlands

2. Rayless chamomile
Matricaria discoidea
> [Matricariinae > Matricaria] > [Matricaria discoidea]

https://www.inaturalist.org/observations/51571778
July 1, 2020 in Russia

3. Roman chamomile
Chamaemelum nobile
> [Anthemidinae > Anthemis] > [Anthemis nobilis]

https://www.inaturalist.org/observations/27806765
June 28, 2019 in United Kingdom

4. Dusky Dog-fennel
Chamaemelum fuscatum
> [Anthemidinae > Anthemis] > [Anthemis fuscatum]

https://www.inaturalist.org/observations/22332895
April 11, 2019 in Portugal

5. Stinking Chamomile
Anthemis cotula
> [Anthemidinae > Anthemis] > [Anthemis cotula]

https://www.inaturalist.org/observations/28185677
June 22, 2019 in United States

6. Corn Chamomile
Anthemis arvensis
> [Anthemidinae > Anthemis] > [Anthemis arvensis]

https://www.inaturalist.org/observations/56052477
August 9, 2020 in Poland

7. Yellow chamomile (Golden Marguerite)
Cota tinctoria
> [Cota] > [Cota tinctoria]

https://www.inaturalist.org/observations/50912822
June 19, 2020 in Germany



Diploid or Tetraploid ( 2n = 18, 36)
7. Corn Scentless-chamomile
Tripleurospermum inodorum
> [Tripleurospermum] > [Tripleurospermum inodorum]

https://www.inaturalist.org/observations/32522328
September 11, 2019 in Russia

https://www.inaturalist.org/observations/1893922
July 11, 2015 in somewhere near Russia

8. Sea Mayweed
Tripleurospermum maritimum
> [Tripleurospermum] > [Tripleurospermum maritimum]

https://www.inaturalist.org/observations/43531953
April 26, 2020 in New Zealand

2n = 18, 54
Genus [Tanacetum]
Go to Appendix IIA


Reference : Flora of North America@efloras.org

  1. www.efloras.org/flora_page.aspx?flora_id=1 > Volume 19
  2. www.efloras.org > Floras of North America >

Lähetetty 10. lokakuuta 2021 10:31 käyttäjältä lunababy22 lunababy22 | 0 kommenttia | Jätä kommentti